The nutrient profiles of other muscle meats are similar, although they contain less zinc. Interestingly, pork is especially high in the vitamin thiamine, providing 63% of the RDI per 3.5 oz (100 grams) (3).

Liver and other organs are also high in vitamin A, vitamin B12, iron and selenium. They're also an excellent source of choline, an important nutrient for brain, muscle and liver health (4).

Bottom Line: Meat is an excellent source of protein and several vitamins and minerals, including vitamin B12, niacin and selenium.

When they're grilled, barbecued or smoked at high temperatures, fat is released and drips onto hot cooking surfaces.

This produces toxic compounds called polycyclic aromatic hydrocarbons (PAHs) that can rise up and seep into the meat.

PAHs are carcinogenic, meaning they can cause cancer. However, minimizing smoke and quickly wiping away drippings can reduce PAH formation by up to 89% (5, 6, 7).

Heterocyclic amines (HAs) are formed when meat is heated to high temperatures and forms a dark crust. HA levels have been shown to rise during extended cooking times and with lengthy cooling down after cooking (8, 9).

Nitrates are additives in processed meats that were formerly considered carcinogenic, but are now considered harmless or even beneficial.

However, researchers disagree about whether similar additives known as nitrites (with an "i") increase cancer risk (10, 11).

Bottom Line: Cooking food at high temperatures or for long periods of time can increase the production of toxic byproducts capable of causing cancer.

Is Red Meat Bad?

However, in nearly every study, the association was between cancer and well-done meat, PAHs or HAs, rather than red meat itself. These studies indicate that high-heat cooking had a very strong effect.

Of all cancers, colon cancer has the strongest association with red meat intake, with dozens of studies reporting a connection.

Aside from a few studies that didn't distinguish between processed and fresh meat or cooking method, increased risk seems to occur mostly with higher intake of processed and well-done meat (20, 21, 22, 23, 24, 25).

In a 2011 analysis of 25 studies, researchers concluded that there was insufficient evidence to support a clear-cut link between red meat and colon cancer (22).

Other Factors That May Affect Cancer Risk

While red meat cooked at high temperatures may increase cancer risk, white meat doesn't seem to. In fact, one study found that poultry consumption was linked to a reduced risk of colon cancer, even when cooked to the point of charring (20, 22, 24).

Animal and observational studies suggest that, in addition to toxic compounds created during high-heat cooking, heme iron found in red meat may play a role in colon cancer development (26, 27).

In addition, some researchers believe processed meat may potentially lead to inflammation in the colon that increases cancer risk (28).

In one study, adding calcium or vitamin E to cured meat reduced levels of toxic end-products in the feces of humans and rats. What's more, these nutrients were found to improve pre-cancerous colon lesions in the rats (29).

It's important to realize that because these studies are observational, they only show a relationship and cannot prove that red or processed meat causes cancer.

However, it definitely seems wise to limit your consumption of processed meat. If you choose to eat red meat, then use gentler cooking methods and avoid burning it.

Several large observational studies exploring meat intake and heart disease have found an increased risk with processed products. Only one study found a weak association for red meat alone (30, 31, 32, 33).

In 2010, researchers performed a massive review of 20 studies with over 1.2 million people. They found that consuming processed — but not red — meat appeared to increase heart disease risk by 42% (30).

However, these studies don't prove that a high intake of processed meat causes heart disease. They only suggest that there may be a relationship.

Some controlled studies have found that frequent meat consumption, including high-fat varieties, has a neutral or positive effect on heart disease risk factors (34, 35).

Bottom Line: Processed meat has been linked to heart disease in some studies, while controlled studies have shown that meat may have a neutral or beneficial effect.

Several large studies have also shown an association between processed or red meat and type 2 diabetes (30, 36, 37, 38, 39, 40, 41).

One review of three studies found that consuming more than half a serving of red meat daily increased the risk of developing diabetes within four years by 30%, in part related to weight gain (37).

However, it's possible that the people who ended up with diabetes had engaged in unhealthy behaviors, such as consuming too many refined carbs, eating too few vegetables or simply overeating in general.

In studies on low-carb diets, which tend to be high in meat, blood sugar levels and other diabetes markers tend to go down (42).

Bottom Line: Some observational studies show a relationship between red and processed meats and increased diabetes risk. However, this may also depend on other dietary factors.

In one study, researchers found that although there was a relationship between frequent red meat consumption and obesity, people who ate the most also took in about 700 more calories daily than those who ate less (44).

Again, these studies are observational and don't account for other types and amounts of food consumed on a regular basis.

And although red meat is frequently linked to obesity and weight gain while white meat isn't, one controlled study found no difference in weight changes among overweight people assigned to eat beef, pork or chicken for three months (45).

Another study in people with prediabetes found that weight loss and body composition improvements were similar whether subjects consumed diets based on animal or plant protein (46).

In one study, 10 obese postmenopausal women followed an unrestricted paleo diet with 30% of calories as mainly animal protein, including meat. After five weeks, weight decreased by 10 lbs (4.5 kg) and belly fat decreased by 8%, on average (47).

Bottom Line: While some observational studies have linked red and processed meat intake to obesity, overall calorie intake is key. Controlled studies have shown that weight loss can occur despite high meat intake.

Some people choose not to eat meat because they don't believe in killing animals for food when there are other ways to meet nutrition needs.

This is a valid point of view that should be respected.

Others object to animals being raised in large, industrial complexes that are sometimes referred to as "factory farms," which is also very understandable.

These farms are overcrowded and often don't allow animals to get sufficient exercise, sunlight or room to move. To prevent infection, livestock are often given antibiotics, which can lead to antibiotic resistance (62, 63).

Many animals are given steroid hormones like estrogen, progesterone and testosterone to speed growth. This raises additional health and ethical concerns (64).

The environmental effects of factory farming have also been criticized, particularly the waste produced during raising and slaughtering, as well as the high cost of grain-based meat production (63, 65, 66, 67).

Fortunately, there are alternatives. You can support small farms that raise animals humanely, don't use antibiotics or hormones and provide their animals with natural diets.

Bottom Line: Some object to killing animals for food, inhumane conditions on industrial farms or the environmental effects of raising livestock.